1. Field of the Invention
The present invention relates to a flock transfer sheet and a flock transfer printing process using the aforementioned flock transfer sheet, and more particularly to a flock transfer sheet adapted for transferring a pile layer made of short fibers dyed to form a pattern of single color or multicolor to a blank stuff, such as a textile fabric or other substrate, to be transferred with the pattern and a flock transfer printing process using such a flock transfer sheet.
2. Prior Art
A flock transfer printing process has been known in the art, in which a pile layer is preliminarily formed on a textile fabric by flocking short fibers and then a pattern is directly printed on the thus flocked pile layer by the use of a printing ink containing a pigment or a resin-bonded pigment color for textile printing followed by fixing the pigment to the short fibers of the pile layer by means of a binder to effect coloring. However, the flock printed matter manufactured by this known process and colored with pigments has disadvantages that it is inferior in color fastnesses to rubbing and crocking that the feeling of the printed portions becomes stiffish and that the printed color lacks brightness and deepness.
In order to improve the feeling of the printed portions and to improve the brightness and deepness of the printed color, it has been proposed to dye the pile layer of short fibers preliminarily flocked on a blank textile fabric with the use of dye. However, whatever dyes are used in practical operation of this known process, it is necessary to after-treat the printed matter through additional steaming and rinsing steps which require a complete waste water treating plant to avoid the pollution problems, thus resulting in considerable increase in investment for such facilities.
Japanese Patent Publication No. 35619/1978 discloses another process which comprises the steps of flocking a release paper sheet with short fibers to form a flocked sheet having a pile layer of short fibers, printing a pattern on the thus flocked sheet using a printing ink containing a pigment to form a flock transfer sheet colored with the pigment, applying the thus formed flock transfer sheet closely on a textile fabric to transfer the pile layer on the textile fabric, and then peeling off the release paper sheet from the pile layer to form a flock printed matter. However, according to this known process, the face of the pile layer of short fibers which has contacted with the release paper sheet forms the upside face of the final printed product. Accordingly, it is required that the printing ink containing the pigment penetrates through the pile layer into the surface area of the release paper sheet in order to form a uniform colored pattern. However, if the printing ink is allowed to penetrate into the surface area of the release paper sheet, the printed images forming the pattern become inevitably thickened and obscure to make it impossible to precisely reproduce a fine or halftone pattern with attendant disadvantage that the feeling of the transfer-printed fabric becomes stiffish.
A further sublimation transfer printing process has been known to the art by French Pat. No. 1,223,330, in which the common sublimation printing method is disclosed. As a method utilizing this known process, a flocked sheet is formed by flocking short fibers on a textile fabric in a desired pattern to form a pile layer, and a separate transfer sheet printed with the same desired pattern is prepared using a printing ink containing a heat-sublimable or heat-vaporizable dye. Then, the transfer sheet is overlaid on the flocked sheet while precisely registering the printed pattern of the former with the contour of the flocked portion on the flocked textile fabric and heated under pressure, whereupon the dye contained in the printed ink is sublimated or vaporized to dye the pile layer so that the printed pattern is transferred to the flocked textile fabric to form a flock printed matter. Although the flock printed matter produced by this known process is improved in bright color and comfortable touch or feeling over the products produced by the preceding known processes in which pigments are used, it has a disadvantage in that halo and ghosting phenomena tend to occur at the heat transferring step due to the difference in heat-shrinckage percentage between the transfer sheet and the flocked textile fabric to which the printed pattern is transferred.
I have already proposed a flock transfer printing process for producing a flock printed matter which is excellent in feeling and printed with a multi-colored pattern or image of bright color. (See Japanese Patent Publication No. 36058/1978.) In this process previously proposed by me, short fibers are flocked on a release paper sheet to prepare a flocked sheet forming a pile layer of short fibers. Separately, a transfer pattern is printed on another sheet of paper using a printing ink containing a heat-sublimable or heat-vaporizable dye followed by applying a hot melt adhesive on the exposed face of the transfer pattern formed of the printing ink. Then, the pile layer of the flocked sheet is peeled off from the release paper and overlaid on the transfer sheet to apply one face of the pile layer to the printed pattern born on the transfer sheet through the hot melt adhesive. An adhesive is coated on the other face of the pile layer, to which a textile fabric is applied through the adhesive. Then, the entire laminate structure is heated under pressure to transfer the printed pattern to the pile layer and concurrently to adhere the pile layer to the textile fabric by means of the adhesive. Finally, the sheet of paper used for the base sheet of the transfer sheet is peeled off to produce a finished product of a flock printed matter. However, this process is disadvantageous in that the heating time is essentially prolonged since the dye shall penetrate or permeate through the hot melt adhesive onto the short fibers during the heating step. A further and more serious disadvantage of this process resides in that the resinous material used as the hot melt adhesive tends to adhere to the surfaces of the short fibers resulting in loss of comfortable touch which is the desired characteristic feature of the flocked textile and the resultant product has the appearance and feeling resembling to a non-woven fabric. Moreover, in case where a plurality of pile layers is transferred and adhered to a textile fabric, a delicate and time-consuming operation is required for the precise layout and arrangement of the patterns formed by said plurality of pile layers, otherwise a considerable amount of defective products is resulted.